1. Field of The Invention
The invention relates to the field of electromagnetic accelerators, in particular to electromagnetic catapults.
2. Background Information
The acceleration of flying bodies or projectiles with the aid of electromagnetic catapults has known advantages over conventional driving methods operating on the basis of internal combustion engines or by using explosion pressure. Electromagnetic accelerators can be technologically grouped with linear drives or motors, but are characterized by very short periods of operation. Compared to the conventional design of linear motors, for example as used in automobile transportation, in electromagnetic accelerators, extraordinarily high force densities are realized if the loads occur only very briefly.
A basic electromagnetic accelerator includes a primary coil arrangement for a stationary portion and a moving translator equipped with one or a plurality of secondary coils. The respective motion state, i.e., position and velocity, of the translator must be taken into account in determining the energy requirements of the coils for operation. The necessary electrical power depends on the mechanics of the acceleration process, that is, on mass, final velocity and acceleration path. However, it is also very much determined by the efficiency of the conversion of electrical energy into mechanical energy. The latter is a function of the intensity of the interaction between the magnetic field and the electrical currents. The field-current interaction is also closely interrelated with the forces acting on the coils. Since a relatively inefficient field-current interaction requires the use of increased electrical currents to obtain the required accelerating force, this also creates power loss problems and consequently higher thermal effects. The realizability of very high performance transducers therefore depends greatly on the intensity and efficiency of the current-field interaction.
In the topology of conventional coaxial, cylindrical coil electromagnetic accelerator, in which stator coils and translator coils form a circularly cylindrical arrangement, conditions are rather unfavorable and result in inefficient electromechanical energy conversion, as well as high mechanical and thermal stresses on the coils.